"... Somethings you'll do for money and some you'll do for fun, But the things you do for love are going to come back to you one by one..."
I find writing to be the best way for me to really understand a subject. Something about writing makes me sort out and organize my thoughts, and so on my mathematical journey I have written a fair deal of notes about things -- mostly commutative algebra and algebraic geometry stuff. Someday I plan on going through these, posting the ones, which I think might be useful to others and are not too out of shape. Until I get around to doing this enjoy Eisenbud Cake!